Synchronizing an PXIe-5644 generator and analyzer is supported for I/Q carrier frequencies from 375 MHz to 3.0 GHz.

For I/Q carrier frequencies below 375 MHz, you cannot share the LO between an analyzer and generator because the PXIe-5644 requires the LO frequency for the analyzer to be twice the I/Q carrier frequency. If your I/Q carrier frequency is below 375 MHz, you must provide an LO signal to the LO IN terminal that is twice your I/Q carrier frequency.

For I/Q carrier frequencies above 3.6 GHz, the expected LO IN (RF OUT 0) power is 3 dBm, but the expected LO IN (RF IN 0) power is 0 dBm. You can share the LO between an analyzer and generator in this range, but specifications degrade due to the power level error at LO IN. The impairments on the device using an external LO also degrade in this range.